I sometimes get into debates about scientific issues with what could be called “bush philosophers.” People who have learned a little (sometimes even a lot) about philosophy but have no real idea of how science works or proper concepts of the philosophy of science. Consequently they sometimes end up making claims, or advancing arguments and justification, about reality which are nothing more than fanciful from a scientific viewpoint.

One justification I commonly hear from such people, particularly theologians, philosophers of religion and those under their influence, is the “inference to the best explanation.” I recognise that this is a recognised philosophical and epistemic process – it’s just that every time I hear that justification I know from experience I will be presented with a bit of motivated “reasoning” or “logic” to justify the proponents strong belief and ridicule different beliefs.

Inference to best explanation and its problems

For example, “Andrew” (sorry don’t know any more about him) claimed to be using the ’Inference to the Most Favored Hypothesis’ in his postComparing the Old & New Teleological Arguments. Boiled down he believes that observed “fine-tuning” of physical constants in the universe is “more probable given the hypothesis of theism as opposed to” an atheistic one. Similarly a local philosopher of religion, Glenn, declares a belief in a god based on this postulate being the “best explanation of the existence of moral facts.” For good measure he in the end adds appeals to a god as the “best explanation of the origin of the universe,” “the fine tuning of the Universe for the existence of intelligent life,” “the objectivity and transcendence of beauty” and “the best explanation for the historical facts concerning Jesus of Nazareth, along with any arguments for the reliability of Scripture.” (see Occam’s Razor and the Moral Argument for Theism).

Whew – you can see that “the inference to the best explanation” does a lot of the heavy lifting for the theologically inclined. Or at least their “bush philosophers.” Problem is that these opportunist users of this “inference to the best explanation” ignore the problems that commonly haunt the method. Problems that have been well understood.

Underconsideration – not considering all relevant explanations available. How can one determine the “best” explanation if the one closest to the truth is not even considered.

Subjective judgement – “explanatory goodness is too subjective a quality to be correlated with objective truth.” Such judgements, like beauty, are in the eye of the beholder.

I think the above examples of theistic use of “inference to the best explanation” illustrate the mistakes of underconsideration and subjectivity in spades. From the perspective of a scientist who is used to inference, to arguments and to comparing hypotheses or “explanations” some things stick out like a sore thumb when the theologically inclined resort to this inference:

1:No real testing against reality.

They rely purely on argument, reasoning or logic – motivated argument, reasoning and logic at that. If facts or evidence are referred to this is usually cherry-picked, distorted or exaggerated. And there is never any idea of producing an hypothesis or explanation for the purpose of testing against reality. One is asked to accept the idea purely on argument. It’s like the buyer of a car being refused a test drive.

Any explanation worthy of the name must surely make predictions about the real world, and preferable testable predictions. How else can we make anything like an objective judgement. How can we compare a number of available explanations for their real explanatory ability?

2: The favoured explanation is usually vague

Of course the favoured explanation is always some form of “god did it.” Inevitably the concept of the god is pretty open ended or vaguely described. There is never any question that the god hypothesis itself could possibly be tested. Quite the opposite. When any testing is suggested ad hoc adjustments are rapidly made to the hypothesis to ensure it remains untestable.

As for the specific explanations – this always seems to be left at a level of some sort of magic. Their god clicked her fingers and the universe came into existence, the appropriate values of physical constants were chosen, objective moral truths were declared, etc. Never any mechanism. One can’t even get the picture of a bearded and robed god adjusting the knobs on his universe-creating machine so as to guarantee the evolution of intelligent life.

Any “explanation” comprising such vagueness is not a real explanation. Serious explanations should contained structured hypotheses, using existing knowledge, suggesting observations, making predictions. And it should have some degree of plausibility, credibility, even if some aspects still await scientific verification.

3: All reasonable candidate explanations are not considered.

Because the prime motivation is to provide an argument for their own pet belief there is no real interest in considering all the possible explanations that can be inferred. In fact, those making the argument may not even be aware of existing candidate explanations and may lump them all into a generalisations such as the “atheist explanation.”

Usually this is bad enough when admitting there are scientific alternative candidates. But I would have thought if you are going to propose an explanation which involving your own preferred god, you should also include explanations which involve other gods or beings. Explanations based on myths of other religions.

The candidate “explanations” available for comparison and judging would be numerous indeed.

4: God-of-the gaps worst explanation

In effect the vagueness and lack of structure common to such theistic “best explanations” mean they boil down to the god-of-the gaps. Anything they don’t understand can be “explained” by postulating their god. No mechanism required, no testing against reality possible. And no real consideration of alternative explanations. Even though these alternatives may have structure, be more plausible or credible, and can offer ways of testing or verification through their predictions.

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